1. Field of the Invention
This invention relates to a new engine cooling system and to new structure therefor as well as to new methods of making such a system and such structure.
2. Prior Art Statement
It is known to provide an engine cooling system comprising a housing means having an inlet and an outlet, and a thermostat construction disposed in the housing means between the inlet and the outlet for controlling the degree of fluid flow therebetween, the thermostat construction comprising a valve seat unit, a valve closure unit for opening and closing the valve seat unit, spring means operatively interconnected to the valve closure unit to tend to close the same against the valve seat unit, and a temperature responsive device comprising a piston member and a cylinder member that are adapted to provide relative movement therebetween when the device senses certain temperatures, one of the members being interconnected to the valve closure unit to move the same in unison therewith in opposition to the force of the spring means when the other of the members is fixed from movement relative to the housing means. For example, see the Wagner et al U.S. Pat. No. 4,548,354.
It was suggested by others that it would be desirable to provide a cooling water thermostat for an engine cooling system that will control at two different temperatures, such as one for summer driving and one for winter driving or one for heavy engine loads and one for normal driving. However, no structure was suggested for accomplishing this feature.
It is also known to provide a piston and cylinder temperature responsive device that will operate in two different temperature ranges. For example, see the Schwartz U.S. Pat. Nos. 3,438,256; 3,381,469 and the Jackson et al U.S. Pat. No. 3,989,058. No. 3,381,469 and the U.S. patent to Jackson et al, No. 3,989,058.
It is also known to provide an electrical heater in combination with a piston and cylinder temperature responsive device for causing the piston member to be extended relative to the cylinder member when the electrical heater means is being operated. For example, see the Noakes et al U.S. Pat. No. 3,696,611; the Cook et al U.S. Pat. No. 4,666,081 and the Nouvell et al U.S. Pat. No. 4,685,651.